A Surface Acoustic Wave Pumped Lensless Microfluidic Imaging System for Flowing Cell Detection and Counting

The future point-of-care diagnostics requires miniaturizing the existing bulky and expensive bioanalysis instruments, where lab-on-CMOS-chip-based technology can provide a promising solution. In this paper, we presented a surface acoustic wave (SAW) pumped lensless microfluidic imaging system for flowing cell detection and counting. Different from the previous lensless systems, which employ external bulky syringe pump for cell driven, the developed system directly integrates the SAW pump on the CMOS image sensor chip to drive the cell-containing microfluid. Moreover, an efficient temporal-differencing-based motion detection algorithm is proposed for continuous flowing cell detection and counting. Experimental results show that the SAW pump can drive the cells to flow at different driven powers, and also can keep the channel temperature below 40 °C so as not to harm the cells. The human bone marrow stromal cells flowing in the microfluidic channel can be automatically detected and counted with a low statistical error rate of −6.53%. The developed system thereby is competitive for point-of-care cell detection and counting application.

I. Introduction

The world population is rapidly aging with the proportion of people aged 60-year-old and over growing faster than any other age groups [1]. Along with the aging society also come special biomedical diagnostic needs and associated challenges. Conventional biomedical diagnostic instruments such as microscopy and flow cytometer for cell detection and counting have improved the early diagnosis and accurate monitoring of existing diseases through blood cell testing [2]. However, these diagnosis systems are usually bulky and sophisticated, hence are expensive, only available in established hospitals or clinics, and require professional personnel to operate. As a result, portable and affordable biomedical devices that miniaturize the traditional bulky and expensive bio-analysis instruments are imperative for the future point-of-care (POC) diagnosis [3], [4]. And various meaningful POC diagnostic systems have been developed recently [5]–[10], such as a smartphone-based electrochemical analyzer and a tumor cell cytometer demonstrated by Guo et al. for biomedical diagnostics.